Normally-open reed switches are typically passive electro mechanical components, principally used as electrical switches which has a basic structure of packing two reeds in a glass tube, two reeds are overlapping in position and separated by a small gap between the two reeds to form a opened state. When operating, imposing external magnetic field on the reeds to force both electrically conducting to form a closed state, and turning to the original open state when the external magnetic field disappeared. Reed switch is principally used to control the system circuit conducting situations, which must be high efficiency, high reliability, high accuracy and rapid response.
Various electrical and mechanical components, e.g. relays, solenoids, valves, sensors, inductance components, micro gear and other electro mechanical components, gradually develop towards miniaturization and low power that push the reed switches forward to miniaturization. The Micro Electro Mechanical Systems (MEMS) is the most mature technology in various miniaturizing manufacturing techniques that the electro mechanical component produced with MEMS methods has smaller volume and is able to configure diversity functions that is also push forward the research and development of the reed switch/micro relays with MEMS technology.
It is worth noting that the reed produced with the MEMS technology in the prior art principally designed as normally open structure, for the reason of the main steps of MEMS process, including photolithography, etching, doping, deposition, etc., is more suitable for forming a continued laminated structure, but many difficulties will be encountered when implementing said steps in producing a non-continuous open structure in interlayer and then forming a normally closed structure. For that reason, the micro reed switches with MEMS process currently designed as a normally open structure.
However, contrary to the normally open structure, there is a need for the normally closed structure, since the normally-closed reed switches including the normally closed structure are still widely used in many MEMS based applications or products. Therefore, the present invention provides a novel method for manufacturing a micro normally closed reed switches which can be simply produced by MEMS process.